Combos or combo bins are large open topped containers with a bottom that typically have no flaps or other structure on the top edges. Combo bins are often used to hold flowable material. An example of a combo bin is an open top container that generally fits a conventional pallet of 48″×40″ (length by width) pallet.
Flowable material refers to material that may or may not have some liquid content, such as juice, brine or free water that oozes or drips from solid material. Examples include meat, such as ground beef, meat cuts and chicken all of which emit purge, a liquid substance. Pickles in brine would be another example. Other examples include plastic pellets and grains. Combo bins of such flowable materials that contain liquid are subjected to hydraulic pressures from the liquid content in the flowable material. The greater the liquid content, the more flowable the material and the greater the hydraulic forces on the combo bin when filled.
Combo bins often deform in shape due to the forces imposed by their contents being much greater than the bending stiffness of the bin material and relative panel sizes. This is further exacerbated when containers are elongated so that some of the panels are wider than others.
When paper board containers are elongated and exposed to hydraulic forces and/or time, the shape of the container changes. The open top of an empty container initially matches the shape and profile of the bottom of the container. However, as the container is filled, the shape deforms because the top of the container is unconstrained. Though an optimal shape under internal loading is round (the top would “like to become” a circle), the bottom structure adds additional constraints and forces to the wall panels that form the container. Essentially the top of the container has a tendency to become a 90 degree shifted image of the container footprint. When equilibrium is reached, the width of the container at the top may actually end up greater than the length of the container at the bottom due to spouting. The term spouting refers to the buckling of one or more side wall panels of the container along a top edge thereof. Typically, a spout is V-shaped and comprises or consists of a region of progressively decreasing triangular cross section moving downwardly away from the top edge of the buckled side panel. The resulting spout projects outwardly beyond the top edge of the panel that would be present if no spouting takes place. The hydraulic or other forces of the contained product can cause panel buckling or false scores (scores in the form of creases that form on their own due to force or defect), typically near the midpoint, left to right, of a container panel. The largest width panels buckle or break first and form spouts with subsequent buckling typically in the next largest panels. Often the largest panels only buckle at or near the middle of their width as such buckling creates a significant relief and the remaining sub-panels are too small (relative to the stiffness of the materials) to sub-divide or buckle into additional panels.
This singular buckling or break in the largest width panels can cause the top of the container to flare outward in an angular fashion. This spouting can cause the upper portion of the container to exceed the width of the transportation platform or pallet. This can pose significant challenges when pallets with containers thereon are placed in a confined space, such as on a racking system.
As a specific example, consider the prior art combo bin 8 shown in FIGS. 1-3. With reference to these figures, this combo bin is comprised of a plurality of upright corrugated paper board wall panels that have respective bottom forming panels that are interconnected to form the base or bottom of the bin. The wall panels include first and second end panels 10, 12. End panel 10 is positioned between a first set of diagonal corner panels 14, 16 (panel 16 being formed from two sub-panels 18 and 20 that are glued together). Diagonal or corner panels 22, 24 are formed at the opposite end of the container with wall panel 12 there between. The illustrated container includes opposed side panels 30, 32 that are the widest panels of the combo bin 8. The combo bin is shown on a pallet 33 that can be a conventional pallet that is 40 inches wide by 48 inches long.
The side panels 30, 32 start out as vertical straight or planar side walls when the combo bin is empty. When empty, the illustrated combo bin 8 is an elongated octagonal shape. The end and corner wall panels 10, 14, 16, 12, 22 and 24 can be the same width. Alternatively, they can be of different widths; for example the end wall panels 10 and 12 can be wider than the corner panels. A liner, such as a large plastic bag 40, can be placed in the combo bin for receiving contents deposited in the bag. As the combo bin is filled, the hydraulic pressures (if the contents contain liquid) become greater as the flowable material is added to the bag 40. Eventually the hydraulic forces can reach a level that causes the widest panels, in this case side panels 30, 32, to buckle. This buckling is indicated at locations 42, 44. In effect the side walls 30, 32 end up with an additional fold at these buckling locations. Consequently, the overall width of the combo bin is expanded between the buckling locations.
In effect, a break or crease 42, located approximately in the center of the side panel, subdivides the side panel 30 into respective panels 43 and 45. In addition, the buckle 44 in effect subdivides the side panel 32 into sub-panels 47 and 49.
With reference to FIG. 2, the buckling at 42 thus forms an angular spout at this location in that the upper portion of the combo bin projects outwardly a greater extent at the location of buckle 42. In addition, the buckle 44 causes the panel 32 to form a spout with the upper end of the panel extending outwardly at the location of buckle 44. As a result, the overall width of the combo bin increases and can be greater in width at its widest location than the width of the pallet 33. The width at the widest location can extend a significant distance beyond the adjacent side of the pallet. This creates problems, such as when the pallets are moved to storage locations, as the over width bins can interfere with the ability to place the pallets next to one another or in racks.
With reference to FIG. 3, a spout 42 is shown from a side elevation perspective. Respective dashed lines 50, 52 are illustrated for purposes of explanation. In general, as the side wall 30 tends to fail, initial buckling appears to happen along respective lines 50 and 52 that are typically at respective angles A and B relative to the bottom edge 53 of the side panel 30. Angles A and B typically range from about 30 to 45 degrees, but can vary depending upon the failure of the container due to hydrostatic hydraulic forces.
There have been various attempts to address the change in shape of these types of containers. The most historically common approach uses bands and/or internal tape built into the structure of the corrugated paper board. These materials do not control the shape of the container per se, but do attempt to constrain the growth in the circumference of the container and thus restrict some of the more severe deformations. However, because the stretch of many of these band materials is on the order of or greater than the stretch of the paper board forming the container, they typically do not effectively limit the spouting type behavior of combo bins.
FIG. 4 illustrates a combo bin with two lower bands or straps 60, 62 and one upper band or strap 64. For convenience, the various wall panels in the embodiment of FIG. 4 have been assigned the same numbers as in FIG. 1. As can be seen in FIG. 4, the straps 60, 62 and 64 did not prevent the buckling at 42 and 44 and the corresponding spouts at the upper ends of the combo bin at these buckling locations. One reason that bands do not help is that the overall perimeter of the upper portion of the combo bin does not dramatically increase as the combo bin is filled, but primarily changes shape.
Another approach does not attempt early control of the bulge. Instead, the combo bin is left to deform in an uncontrolled fashion until an upper parabolic score, extending from upper corner to upper corner of the widest panel, tries to impede the formation of the spout. This upper parabolic score is positioned above the horizontal center line of the combo bin. This presents several problems. The uncontrolled nature of the start reduces the reliability that the parabolic score will actually mitigate the spout formation and thus reduce the overall combo width. Secondly the size of the resulting panel lends itself to subsequent fracture from hydraulic forces and spouting even if it initially performs as desired. Thirdly the upper parabolic score is limited in elongation aspect ratio, which is exacerbated by increasing panel widths.
Therefore, a need exists for a combo bin with structures that control the deformation of side walls of a combo bin, particularly when they are filled with a flowable material that exerts hydraulic pressures on the side walls. These and other aspects of this disclosure will become apparent from the description below and accompanying drawings.